The learning curve and safety of continuous intraoperative vagus nerve monitoring in thyroid surgery

INTRODUCTION

Continuous intraoperative nerve monitoring allows for continuous feedback on the integrity of the recurrent laryngeal nerve (RLN) and the quality of its induced myogenic potential. The aims of this study were to assess the time requirements and risks associated with vagus nerve electrode placement when learning the technique.

METHODS

This is a prospective observational study carried out in a single otolaryngology department at the start of a trainee's placement. A total of 40 vagus nerve dissections in 31 consecutive operations (22 hemithyroidectomies, 9 total thyroidectomies) using automatic periodic stimulation (APS, Medtronic) are included. Of the electrode placements, 10 were performed by the trainer and 30 by the trainee. The time required for each surgical step and complications relating to vagus nerve dissection were recorded.

RESULTS

The average (median+IQR) total additional time attributable to vagus nerve dissection, electrode placement and baseline electromyogenic assessment was 3.1mins (2.5-3.3) for the trainer and 4.8mins (4.1-5.3) for the trainee (p<0.0001). There was a downward trend in time requirement for the trainee (not statistically significant, p=0.080). Total operative time was 38min (35-45) for hemithyroidectomy and 56min (53-62) for total thyroidectomy. There was a mix of benign (74%) and malignant (26%) histology, no intraoperative complications relating to autonomic dysfunction and one (2.5%) transient nerve palsy.

CONCLUSIONS

Operative time attributable to vagus nerve electrode placement is short and the procedure is easy to learn. Appropriate surgical technique and careful anaesthetic considerations allow monitoring to be performed safely, and may reduce the rate of RLN palsy.

Solid-Phase synthesis of a dendritic peptide related to a retinoblastoma protein fragment utilizing a combined boc- and fmoc-chemistry approach

Dendritic peptides, often presented as multiple antigen peptides (MAPs), are widely used in immunological-based fields of research, although their synthesis can be extremely challenging. In this paper, a tetrameric dendritic MAP-like presentation of the retinoblastoma protein [649-654] sequence (4RB(649-654)) has been prepared using solid-phase peptide synthesis (SPPS) methods. During the synthesis of this dendritic molecule, numerous modifications to the synthetic protocols were examined. These modifications included the introduction of a combination Boc- and Fmoc-chemistry approach and also the use of 1,8-diazabicyclo[5.4.0]-undec-7-ene as a Fmoc-deprotection agent. The use in combination of Boc- and Fmoc-based synthetic strategies resulted in the production of the desired peptide molecule, 4RB(649-654), in high purity and acceptable yields following purification by reversed phase HPLC.

Effects of social proximity on multiple aggressive behaviors

We systematically manipulated social proximity to examine its influence on multiple topographies of aggression. Aggression occurred at high levels during close-proximity sessions and at low levels during distant-proximity sessions even though social contact was presented continuously during both conditions. Topographies of aggression emerged sequentially across the close-proximity sessions, and all topographies were reduced to zero following extended sessions of this condition.

Solid phase synthesis of cyclic peptides: model studies involving i-(i+4) side chain-to-side chain cyclisation

Conditions for the synthesis of i-(i + 4) side chain-to-side chain head-to-tail Lys-->Glu and Glu-->Lys linked cyclic peptides related to hypoglycaemic analogues of human growth hormone hGH [6-13] have been examined. The success of the cyclisation reaction with the corresponding resin-bound, partially protected linear peptides was found to be both reagent as well as sequence dependent, with competing inter-chain oligomerisation predominating in some cases. The results also indicated that protection with the bulky Fmoc group of the amino acid residues immediately adjacent to the side chain-deprotected Lys and Glu residues, which participate in the cyclisation reaction, enhanced the rate of lactam formation.

The Women's Health Trial Feasibility Study in Minority Populations: design and baseline descriptions

The Women's Health Trial: Feasibility Study in Minority Populations (WHT:FSMP), a randomized trial of 2208 women, was conducted to investigate three questions. First, can women from minority and low-socioeconomic-status populations be recruited in numbers sufficient to evaluate a dietary intervention designed to lower fat intake. Second, the efficacy of a low fat, increased fruit/vegetable/ grain product intervention for reducing fat consumption. Third, will participation in the intervention lower plasma cholesterol and estradiol levels relative to the controls. The baseline results showed that an adequate number of minority and low SES women could be recruited to test the study hypotheses. A diverse study population of postmenopausal women consuming a high fat diet was recruited: 28% of participants were Black, 16% were Hispanic, 11% had less than a high school level of education, and 15.5% had household incomes of < $15,000.

Black rubber or clear plastic delivery tubing for nitrous oxide: patient preference

Entonox (a 50:50 mixture of nitrous oxide in oxygen) is given via black rubber corrugated tubing in most obstetric units even though this has been superseded by clear plastic tubing in many operating theatres. This trial has shown that more women in labour preferred using plastic rather than black rubber tubing because it was lighter in weight and devoid of the unpleasant smell associated with the latter. Women also suffered a greater degree of dizziness while using the black rubber tubing. Clear plastic tubing seems a sensible alternative for the delivery of Entonox now that the risks associated with the build up of static charge have little importance. It is cheap, odourless and lightweight, it can be cut to any length, fits standard 22 mm connections, is easy to clean and although durable is potentially disposable.

Proprioceptive accuracy in idiopathic scoliosis

Defects in proprioceptive postural control have been linked to the etiology of idiopathic scoliosis. In particular, a rearrangement of the internal representation of the body has been proposed in these cases. In this study, upper-extremity proprioceptive accuracy was compared among the following groups: 1) patients with idiopathic scoliosis (n = 25); 2) subjects with nonprogressive spinal asymmetry detected by screening in school (n = 23); 3) subjects undergoing behavioral training for nocturnal enuresis (n = 17); and 4) normal subjects (n = 134). A significant inaccuracy was found among the right-handed subjects of the scoliosis and spinal asymmetry groups as compared to the normal group. It is postulated that proprioceptive dysfunction, or borderline function, is a causative factor of spinal asymmetry, which is often observed in early adolescence and which in some cases may be progressive.

Influence of Age on Proprioceptive Accuracy in two Dimensions

Slow arm movements were made over a smooth horizontal table at shoulder height. With visual cues excluded, target position was indicated by the index finger of the nonmoving arm touching the underside of the table. 134 subjects (including 26 left-handed subjects) in the age range 8.0 to 24.6 yr. were examined to see if the results were age-related. Accuracy slightly but significantly increased with age. The younger subjects showed a greater accuracy with the dominant hand—a situation which tended to be reversed in the older subjects.

Influence of age on proprioceptive accuracy in two dimensions

Slow arm movements were made over a smooth horizontal table at shoulder height. With visual cues excluded, target position was indicated by the index finger of the nonmoving arm touching the underside of the table. 134 subjects (including 26 left-handed subjects) in the age range 8.0 to 24.6 yr. were examined to see if the results were age-related. Accuracy slightly but significantly increased with age. The younger subjects showed a greater accuracy with the dominant hand--a situation which tended to be reversed in the older subjects.

Release factor competition is equivalent at strong and weakly suppressed nonsense codons

We have compared the competition between strong or weak suppressor tRNAs and translational release factors (RF) at nonsense codons in the lacI gene of Escherichia coli. Using the F'lacIZ fusions developed by Miller and coworkers, UAG, UAA, and UGA codons at positions 189 and 220 were efficiently suppressed by plasmid-borne tRNA(trp) suppressors cognate to each nonsense triplet. Introduction of a compatible RF 1 plasmid competed at UAG and UAA but not UGA codons. An RF2 expressing plasmid competed at UAA and UGA but had little effect at UAG. Release factor competition against weak suppressors was measured using combinations of noncognate suppressors and nonsense codons. In each case, release factor plasmids behaved identically towards poorly suppressed codons as they did when the same codons were efficiently suppressed. The implications for these studies on the role of release factors in nonsense suppression context effects are discussed.

Rad52-independent mitotic gene conversion in Saccharomyces cerevisiae frequently results in chromosomal loss

We have examined spontaneous, interchromosomal mitotic recombination events between his4 alleles in both Rad+ and rad52 strains of Saccharomyces cerevisiae. In Rad+ strains, 74% of the His+ prototrophs resulted from gene conversion events without exchange of flanking markers. In diploids homozygous for the rad52-1 mutation, the frequency of His+ prototroph formation was less than 5% of the wild-type value, and more than 80% of the gene conversion events were accompanied by an exchange of flanking markers. Most of the rad52 intragenic recombination events arose by gene conversion accompanied by an exchange of flanking markers and not by a simple reciprocal exchange between the his4A and his4C alleles. There were also profound effects on the kinds of recombinant products that were recovered. The most striking effect was that RAD52-independent mitotic recombination frequently results in the loss of one of the two chromosomes participating in the gene conversion event.